A Quasi Two Dimensional Model of Transport Phenomena in Diesel Particulate Filters - The Effects of Particle and Wall Pore Diameter on the Pressure Drop -

摘要

Experimental and numerical studies were conducted on diesel particulate filters (DPFs) under different soot loading conditions and DPF configurations. Pressure drops across DPFs with various mean pore diameters loaded with soots having different mean particle diameters were measured by introducing exhaust gases from a 2.2 liter inline four-cylinder, TCI diesel engine designed for use in passenger cars. A mechanistic hypothesis was then proposed to explain the observed trends, accounting for the effects of the soot loading regime in the wall and the soot cake layer on the pressure drop. This hypothesis was used to guide the development and validation of a numerical model for predicting the pressure drop in the DPF. The relationship between the permeability and the porosity of the wall and soot cake layer was modeled under various soot loading conditions. An equation predicting the porosity of the soot-coated wall and the soot cake layer was derived as a function of the mean diameter of secondary soot particles. The percolation coefficient at which the soot filtering regime changed from wall trapping to cake layer trapping was also determined by considering the filtering efficiency. The model was validated by comparing its output to the results of experimental test cell studies and used to analyze transport phenomena in particular filters.